In multi-cylinder internal combustion engines having electronic injection, it is usually calculated in the engine control unit when and how much fuel is to be injected per cylinder, and when the optimal ignition point will occur. In order for these calculations to be able to be carried out correctly, the respective setting of the crankshaft and the camshaft have to be known. In published European patent document EP 0017933, for example, it is described that the crankshaft and camshaft are each connected to a disk on whose surface at least one reference mark has been applied, and on the crankshaft disk, in addition, a plurality of similar markings, also known as increments, have been applied.
The two rotating disks are scanned by stationary sensors. From the sequence in time of the signals supplied by the sensors in the form of pulses, one may gather a single-valued statement concerning the setting of the crankshaft and the camshaft, and appropriate control signals may be formed in the engine control unit for injection or ignition.
From published German patent document DE 41 41 713, it is known that one may provide a signal-generating wheel at the camshaft, in addition to the one at the crankshaft which has a disk having a plurality of markings and having a bench mark or reference mark formed by two missing markings. This signal-generating wheel at the camshaft has markings of different lengths, adjusted to the number of cylinders, which the phase signal of the phase sensor reproduces. The phase signal of the phase sensor is drawn upon for cylinder identification.
From published German patent document DE 43 10 460, it is known that one may carry out the synchronization of the engine control unit via specially developed camshaft signal-generating wheels, which permit a rapid synchronization using counting of the segment lengths based on the crankshaft signal.